sftp: Fix bug in sftp_mkdir not returning on error.
sftp: Fix bug in sftp_mkdir not returning on error.

resolves: #84

taikoo/libssh,pouete/libssh,mwgoldsmith/ssh,pouete/libssh,DouglasHeriot/libssh,jt1/honeypot-libssh,elastichosts/libssh,taikoo/libssh,mwgoldsmith/libssh,mwgoldsmith/ssh,Distrotech/libssh,robxu9/libssh,robxu9/libssh,kedazo/libssh,wangshawn/libssh,wangshawn/libssh,sebadoom/libssh,DouglasHeriot/libssh,DouglasHeriot/libssh,jt1/honeypot-libssh,pouete/libssh,mwgoldsmith/libssh,elastichosts/libssh,Distrotech/libssh,Distrotech/libssh,nviennot/libssh,nviennot/libssh,sebadoom/libssh,elastichosts/libssh,bigcat26/libssh-mod,mwgoldsmith/ssh,mwgoldsmith/libssh,Distrotech/libssh,mwgoldsmith/libssh,mwgoldsmith/ssh,wangshawn/libssh,pouete/libssh,jt1/honeypot-libssh,DouglasHeriot/libssh,bigcat26/libssh-mod,sebadoom/libssh,kedazo/libssh,jt1/honeypot-libssh,robxu9/libssh,bigcat26/libssh-mod,bigcat26/libssh-mod,kedazo/libssh,nviennot/libssh,taikoo/libssh,wangshawn/libssh,sebadoom/libssh,taikoo/libssh,kedazo/libssh,robxu9/libssh,nviennot/libssh